Conventionally, piezoelectric actuators have been widely used, for example, for driving a magnetic head of a hard disk drive.
A piezoelectric actuator includes a piezoelectric substrate polarized in a predetermined direction. Therefore, when mounted on a device, the piezoelectric actuator needs to be oriented in accordance with the direction of polarization. This means that the orientation of the piezoelectric actuator needs to be identifiable. For example, Patent Document 1 describes a piezoelectric actuator whose orientation is easily identifiable. Specifically, Patent Document 1 describes a piezoelectric actuator in which a silver chloride layer is formed on one of a pair of silver electrodes on opposite principal surfaces of a piezoelectric body which is made of piezoelectric ceramic. Since the silver chloride layer is different in color from the silver electrodes, the orientation of the piezoelectric actuator described in Patent Document 1 is easily identifiable.
Patent Document 1: Japanese Unexamined Patent Application Publication No. 10-294501